Hepatocellular carcinoma (HCC) is the most common of the hepatobiliary (liver, gall bladder and bile duct) cancers and the fourth most common cancer worldwide. National Comprehensive Cancer Network (NCCN) Clinical Practice Guidelines in Oncology: Hepatobiliary Cancers Version 1 (2013). According to the National Cancer Institute's cancer.gov website, it is estimated that around 33,000 new cases of HCC will be diagnosed and 23,000 deaths will occur due to this disease in the United States in 2014. Risk factors for HCC include infection with hepatitis B virus (HBV) or hepatitis C virus (HCV), alcoholic cirrhosis, and other liver conditions, such as hemochromatosis or late stage primary biliary cirrhosis (PBC). NCCN Guidelines, supra. The incidence of HCC in patients with these conditions is sufficient to allow them to constitute a feasible high-risk screening population.
Measurement of serum alphafetoprotein (AFP) and liver ultrasonography at intervals of 6-12 months are used for HCC screening in the high risk population. However, the American Association for the Study of Liver Disease (AASLD) guidelines no longer recommend AFP testing as part of a diagnostic evaluation (see NCCN Guidelines, supra), due to lack of adequate sensitivity or specificity. While high levels of serum AFP can be considered diagnostic of HCC, they occur in only a relatively small percentage of patients with HCC. It has been shown in a meta-analysis by Dr. Singal et al. that measurement of AFP provided no additional benefit to ultrasound screening for detection of early stage HCC. A. Singal, et al., Meta-analysis: Surveillance With Ultrasound for Early-stage Hepatocellular Carcinoma in Patients with Cirrhosis Aliment Pharmacol. Ther. vol. 30 no. 1 pp. 37-47 (2009). However, additional imaging studies and more frequent monitoring are still recommended for patients with rising levels of AFP. Ultrasound evaluations suffer from lack of inter- and intra-operator and machine variability and may be difficult in obese patients. While CT scans with contrast allow for the detection of much smaller tumors or nodules than ultrasound (<1 cm), these cannot be carried out in patients with renal insufficiency and the radiation dose from repeated CT scans in a screening setting may be problematic.
Exploratory serum biomarkers being studied in the context of HCC detection and diagnosis include des-gamma-carboxy prothrombin (DCP), also known as protein induced by vitamin K absence-II (PIVKA-II), and lens culinaris agglutinin-reactive AFP (AFP-L3), an isoform of AFP. Prior art of interest relating to HCC biomarkers includes E. E. Schwegler et al. SELDI-TOF MS profiling of serum for detection of the progression of Chronic Hepatitis C to Hepatocellular Carcinoma Hepatology vol. 41 no. 3 pp. 634-642 (2005); D. G. Ward et al., Changes in serum proteome associated with the development of hepatocellular carcinoma in hepatitis C-related cirrhosis British Journal of Cancer vol. 94 pp. 287-292 (2006); D. W. Ward, et al., Preclinical and post-treatment changes in the HCC-associated serum proteome British Journal of Cancer vol. 95 p. 1379-1383 (2005). Other prior art of interest includes A. Flores et al., Emerging trends in hepatocellular carcinoma: Focus on Diagnosis and Therapeutics Clinical Medicine Insights: Oncology vol. 8 p. 71-76 (2014); L. Li et al., Micro-riboneucleic acids: potential noninvasive biomarkers for hepatocellular carcinoma Journal of Hepatocellular Carcinoma vol. 1 p. 21-33 (May 2014); P. Prieto, et al., DKK1 as a serum biomarker for hepatocellular carcinoma Hepatobiliary Surg. Nutr. Vol. 2 no. 3 p. 127-128 (2013); H. Kim et al., Development of Biomarkers for Screening Hepatocellular Carcinoma using Global Data Mining and Multiple Reaction Monitoring PLoS One vol. 8 no. 5 pp. 1-11 (2013); C. Liu et al., MALDI-TOF MS combined with Magnetic Beads for Detecting Serum Protein Biomarkers and Establishing of Boosting Decision Tree Model for Diagnosis of Hepatocellular Carcinoma Am. J. Clin. Patho. vol. 134 pp. 235-241 (2010); S. Shang, et al., Identification of Osteopontin as a Novel Marker for Early Hepatocellullar Carcinoma Hepatology vol. 55 p. 483-490 (2012).
The development of an improved screening protocol for patients at high risk of developing HCC is an important clinical goal, particularly if it is able to detect early stage HCC. If detected early, HCC can be treated via resection or transplant and 5-year survival rates of 70% may be achieved. See A. Singal et al. paper, supra. However, there are very few approved treatments for unresectable HCC and the prognosis in the later stages of the disease remains very poor, with 5-year survival rates only around 5%. Currently less than 30% of patients are diagnosed early enough to be suitable candidates for resection or transplantation. See A. Singal et al. paper, supra.
This document describes a serum-based test for the detection of HCC in a high risk population using Matrix Assisted Laser Desorption and Ionization-Time of Flight (MALDI-TOF) mass spectrometry, a classifier used in the test, and a method of generation of a classifier for screening high risk patients for early detection of HCC.